NACE Trim Ball Valves

[Sid89]

What are the acceptable materials as per NACE MR0175 (latest version) for the trim of floating and trunnion ball valves? 300 Stainless has become unacceptable. So what materials for valve body, stem, ball, seats, packing, and gaskets are still valid?

 

[SJones]

On what basis has "300 stainless" become unacceptable?

Steve Jones
Corrosion Management Consultant

http://www.linkedin.com/in/drstevejones

All answers are personal opinions only and are in no way connected with any employer.

 

[Danlap]

It is indeed have some implication especially from manufacturer side.
Main reason for this change is due to some findings of sulfide stress cracking. Commonly on spindle. Below is one example for spindle of gate valve made from 316 in sour application with some sulfur content.
Your word 'unacceptable' might be perceived differently by other people. But it is no longer stipulated in the new NACE MR0715.

Aim for wetted parts which borne the 'stress' to comply with NACE hardness limit (maximum 22 HRC). So you may exclude body to be NACE'd.
I think the new table is self-explanatory. Either 410 or Nitronic.
Else, to weld overlay 316 or 17-4PH material with Stellite 6 or 13 Cr. This is not a hustle-free process.
IMO bigger challenge is more on the integrated spindle+plug/wedge design for globe/gate valve with relatively bigger sizes.
One may argue that less susceptible stressed parts e.g. ball, wedge (alone), etc. may not subject for this new rolled-out NACE.

Success,
MR

https://nosuchvalve.com

All valves will last for years, except the ones that were poorly manufactured; are still wrongly operated and or were wrongly selected

http://www.eng-tips.com/faqs.cfm?&rat1=2&fid=376

 

[jbeckhou]

It would depend on the material class and sour service rating. We use 410 SS / TC for our gates DD/EE trim, solid stellite for seats, 410 SS for our body bushings, 4130/410/718/725 for stems, 4130 for bodies, bonnets, packing glands.
Using 316 / 17-4 for seats or pressure controlling parts isn't acceptable for NACE/API applications. Ring gaskets are still made from 316SS.

Petrotrim Services, LLC

http://www.petrotrim.com

 

[Sid89]

So we can still use SS316/S304 for body material of ball valve but those along with 17-4 cant be used for stem, ball, etc.?